Escaping special characters is a usual business in programming and PHP is not an exception either. There are plenty of escaping functions in PHP and we already mentioned some of them that deal with encoding HTML entities. MySQL is also picky when it comes to special characters and it has its own sets and rules which are usually covered with escaping functions such as addslashes. However, when it comes to storing JSON in the MySQL the approach is a bit different.

There are quite a few similar functions in PHP. Some of them are almost identical like echo and print and some have subtle differences which are not obvious at the first glance. We can put htmlspecialchars_decode and html_entity_decode in this category. There is a lot of confusion between notions of HTML special characters and HTML entities so let’s look into the difference.

In certain situations, you could be messing with HTML special characters in a text. At first glance, you might not even notice these are existing in the text. For example, if you’re looking text in a browser these characters will look just like normal characters. But when you peak into the page source you’ll see very different representations, (&amp; for &, &quot; for “, &lt; for <, &gt for > and so on). So how do you convert it to the normal characters?

Sometimes we will need to automate file copying between our servers. For example, our shell script might need to copy the backup from time to time and we don’t want to provide the password in the clean text format. So what we can do about this?

MySQL master-slave replication is well covered so I won’t go deep into explanations and details. This supposes to be a simple how-to tutorial. However, I’m going to pinpoint a few details that might lead you astray while doing this easy setup.

When you enter the field of multiple MySQL instances on one physical server you might run into the trouble. Lack of documentation, cryptic bugs, and insane settings is something you need to get used to. I almost quit a few times in the process and only my habit of trying unusual things when everything logical failed kept me up to the solution.

Recently I run into problems trying to save JSON into MySQL database. Even though MySQL supports JSON type for some time now, there are still plenty of gotchas while you work with it. The situation is pretty critical with special characters. This time we are going to be short and on the topic of invalid JSON characters.

PHP can sometimes be confusing where it shouldn’t be. One area of confusion is the issue with duplicate built-in functions. I’m always inclined to think that developers probably had good reason to make duplicates and the most of the times its good assumption.

But is it always true? Let’s see on the example of echo end print functions.

In the 3rd installment of the Beginners guide to programming, we will explore Central Processing Unit (CPU) and its role in the computer system and programming. I hope that you remember everything from first and second level programming guide. If not, you can refresh your memory before you jump into this one.

We will start exploring CPU role from the perspective of simple question many people are asking these days which is: How many CPU cores do I need?